Controlling device for heat exchanging apparatus



June 12, 1934.

A. L. DAUPHIN CONTROLLING DEVICE FOR HEAT EXCHANGING APPARATUS Filed Dec. 28, 1931 3 Sheets-Sheet 1 Liza 0A:

June 12, 1934. A, DAUPHIN 1,962,952

CONTROLLING DEVICE FOR HEAT EXCHANGING APPARATUS Filed Dec. 28, 1931 3 Sheets-Sheet 2 Fig. 2

I71/6/77Z1V ,7. L, Ida 0AM June 12, 1934. DAUPHIN 1,962,952

CONTROLLING DEVICE FOR HEAT EXCHANGING APPARATUS I Filed Dec. 28. 1931 5 Sheets-Sheet 5 a II, 5

Patented June 12, 1934 UNITED STATES PATENT? OFFICE CONTROLLING DEVICE FOR HEAT EXCHANGING APPARATUS Andre Lucien Dauphin, Paris, France Claims. (01. 62-91.5)

This invention relates to controlling devices for heat controlling apparatus and more particularly for air cooling apparatus.

In well known cold producing and distributing 5 apparatus it has been proposed to immerge a heat exchanging device in a cooling liquid such as brine and the like, the temperature being maintained at the desired value by repeated additions of a cold producing material, for example solid carbon dioxide, but more particularly in the latter case the control of the temperature has been attended with great difiiculty on account of the very low temperature of the cold producing material.

The present device, which overcomes these drawbacks, comprises the combination with a suitable heat exchanger supplied with brine or the like of a device for delivering solid carbon dioxide, dry ice or other suitable cooling material, said device being directly driven by the blower of the heat exchanger, for instance, and having its speed controlled by a suitably balanced thermostatic device, thus permitting the use of said device whatever may be the extreme temperatures to which it is to be subjected.

The accompanying drawings show as an exam- 'ple one form of cold producing plant provided with a heat exchanger supplied with solid carbon dioxide.

Fig. 1 is a sectional elevational view showing the plant diagrammatically.

Fig. 2 is a sectional plan view of Fig. 1.

Fig. 3 is a general view showing diagrammatically the balanced thermostatic device.

The heat exchanger comprises a tank, shown diagrammatically at 1, containing a cooling liquid 2 through which extend tubes 3 in which air from the room to be cooled flows in any desired direction, say upwardly as shown. This air is drawn by suction into a chamber 4, provided at the upper part of tank 1, by an exhausting blower 5 driven from a suitable electrical or other motor located as at 6.

Arranged at a suitable position over the tank 1 is a suitably heat-insulated chute '7 receiving blocks or slabs of solid carbon dioxide the lower one of which bears upon a feeding roller 9, of

bronze or other suitable material, carried in bear-.

ings 10 preferably of lignum vitae or other material not requiring any lubrication, thus permitting the whole apparatus to operate efflciently in spite of the extremely low temperatures resulting from the gasification bf solid carbon dioxide, as the latter is capable of producing a temperature of about C. at which no lubricating material could be successfully employed. The roller 9 is provided with a suitable number of cutters 11 of rustless steel, for example, said cutters being arranged in such a manner that the end of the lower block 8 which bears against the roller 9 will be shaved into chips as the roller is rotated.

In view of the rotation of the roller 9 the latter is provided with a bevel wheel 12 meshing with a bevel pinion 13 which is driven by a variable speed gearing comprising, as shown, two conical friction gears 14, 15, rotatingly mounted on parallel axis but oppositely arranged, both friction gears being engaged with an intermediate friction roller 16 in the form of a spherical segment which is loosely mounted. The spindle 17 of friction gear 15 is driven directly from the shaft 19 of motor 6 by means of a belt or other gearing 18.

The roller 16 is carried in a fork 20 provided at the end of a lever 21 having a stationary fulcrum 22, said lever being connected by a suitable pivoting joint to the driving stem 23 of a compensating thermostatic device.

As shown in Fig. 1, the conical friction gear 14 is provided at its larger end with a cylindrical part 24 corresponding to the temporary disconnected position when the predetermined temperature is exceeded (negatively).

While any thermostatic device may be used, I have chosen the type of device based upon the dilatation of a liquid and adapted to the special conditions obtaining in the present use.

As is well known such devices are only large thermometers controlled by the difference of dilatation between a liquid and the vessel that contains it. In view of the present use however suflicient power must be available for shifting the friction roller 16 in the case the apparatus should offer high resistances, as it is probable it will, by reason of poor maintenance or otherwise. This power should be be available in connection with a stroke sufficient for a rather small gradient of temperature such as 5-8 C. Above all the apparatus should be capable of resisting the high temperatures to which it will be subjected as, for example, in warm countries after the cooling process has been stopped, without incurring the risk of being damaged or put out of order.

In the form of construction as shown the thermostatic device consists of a liquid container 25, for example in the form of a set of tubes immerged in brine 2. These tubes of which there maybe any convenient number, are made of a suitable material the coeflicient of expansion of which is preferably as low as possible. They have a large area in contact with the brine and are connected by a relay tube 26, preferably of a small section, with an active undulated tube 27 (Fig. 3) confined in a tubular guide 28 containing a spring 29 which tends constantly to restore the undulated tube 27 to its contracted condition, when its length is minimum. Metals such as Invar or Elinvar may usefully be used for the body of the thermostat. The active expanding undulated tube 27 is made fast at one end with the tubular guide 28 by means of an internal shoulder 30, while its other end carries the aforesaid stem 23 which is pivoted to the roller-carrying lever 21,,

preferably by means of a suitable slide.

From the relay tube 26 branches off a pipe 31 connected with a compensating undulated tube 32 of suitable capacity mounted in a guide 33 and maintained at its least volume by a counteracting spring 34 the power of which exceeds by a predetermined amount that of spring 29 of active tube 27. Tube 32 bears at its end against hinged catches 35, in any convenient number, having a face inclined at such an angle that said catches only yield under a predetermined thrust of the compensating tube 32, thus operating as an abutment which ofiers a great resistance to the expansion of the tube 32 while offering no substantial resistance to the return movement.

The apparatus operates as follows:-

The motor 6 having been started, for example in view of cooling a room, air is drawn through the tubes 3 the walls of which have been cooled due to their contact with brine 2, thus cooling said air, the speed of rotation of the blower 5 being substantially constant.

In addition to driving the blower, motor 6 controls through the conical friction gears 14, 15, and roller 16 the rotation of the feeding roller 9 the cutters 11 of which shave off the lower slab of solid carbon dioxide into chips that fall into the brine 2 in tank 1. When the temperature in the room rises above a given value, this raises the temperature of the brine 2 and, therefore, of the liquid contained in vessel 25 of the thermostatic device, producing in turn a dilatation of said liquid and the lengthening of the tube 27 the stem 23 of which acts upon the lever 21 in such a manner as to cause the roller 16 to rise along the pulleys 14, 15, thereby increasing the speed of rotation of pulley 14 and, hence, that of feeding roller 9, so that the latter delivers a larger amount of solid carbon dioxide into the brine 2, thus lowering its temperature.

The lowering of the temperature of the room to be controlled operates in the reverse manner to reduce the supply of solid carbon dioxide.

Assuming that the raising of the temperature is normal, the liquid of the thermostatic device will act in the tube 27 alone inasmuch as the compensating tube 32 is held against extension by a much greater resistance, so that said resistance may be considered as being absolute in the normal range of working. However, if the'temperature continues to increase, as the tube 27 is no longer capable of extension the pressure increases in the whole relay system 2631 of the thermostatic device and, by acting in the compensating tube under a given value, causes the catches 35 to yield under the thrust of the compensating tube 32, whereupon the latter will be able to take up the whole dilatation process of the liquid contained in the device.

Upon contraction the spring 34 acting against the compensating tube 32, which is stronger than spring 29, operates first to bring the tube 32 back into the position of Fig. 3; the catches 35 being restored to the position of Fig. 3 under the action of return springs, not shown, whereupon the active tube 27 resumes its normal function.

In the described arrangement the control of the whole apparatus is based upon the temperature of the brine, i. e. not dependent upon the temperature of the air forced by the blower 5. In fact the main object in view has been to devise a commercial apparatus which will not require a great accuracy but is very sturdy. The speed of the feeding roller 9 might however be varied in accordance with the temperature of the air by the use of a thermostatic device of suitable sensitiveness acting indirectly upon the variable spee gear through an energizing mechanism.

The arrangement hereindescribed permits of the whole plant having a sufiicient sensitiveness while allowing it to be subjected free of danger to very considerable increases of temperature such as those resulting from working pauses as in the use of the apparatus in railways, for example, or in tropical countries.

The device for supplying solid carbon dioxide may also consist of a circular plate carrying radial cutters and rotated by a gearing similar to the gearing described.

The arrangement described may be easily applied to a movable air cooling apparatus without impairing its movable character nor increasing substantially the over-all dimensions of the plant. The chute 7 receiving the slabs of carbonic snow may contain a stock of such slabs and said chute will preferably be provided with internal ribs preventing direct contact of the slabs with the walls of the chute itself. The whole chute communicating with the tank oi the heat exchanger operates then as an outlet stack or chimney through which the cold gases produced by the gasification of the solid carbon dioxide escape. The stock of solid carbon dioxide is thus constantly maintained in a flow of cool gas which insulates it from the heatiand prevents it from gasifying.

The variable speed gear for driving the feeding roller may obviously vary in form and arrangement and the whole plant may be made in any size adapted to the purposes in view, whether stationary or movable.

The invention may further be applied to the exchange of heat for any purposes whatever.

What I claim is:

1. A heat exchanger comprising a brine tank, a plurality of tubes extending through said brine tank, means for forcing the fluid to be cooled through said tubes, a feed chute for cooling material in a solid form, cutters cooperating with said chute for slicing said solid cooling material into shavings to be fed into said brine tank, a thermostatic element positioned in said brine tank and means controlled by said thermostatic element for regulating the amount of solid cooling material cut by said cutters.

2. A heat exchanger comprising a brine tank, a plurality of tubes extending through said brine tank, a blower for forcing the fluid to be cooled through said tubes, a motor for driving said blower, a thermostatic element positioned in said brine tank, means for cutting solid cooling material into shavings to be fed to said brine tank, a variable speed gear for driving said cutters, said variable speed gear also being driven by said motor and means controlled by said thermostatic element for varying the speed of said variable speed gear. I

3. A heat exchanger comprising a brine tank, a series of tubes extending through said brine tank, means for forcing the fluid to be cooled through said tube, a thermostatic element positioned in said brine tank, means for feeding solid cooling material to said brine tank, a variable speed gearing for driving said feeding means and means controlled by said thermostatic element for varying the speed of said variable speed gear.

4. A heat exchanger comprising a brine tank, a series of tubes extending through said brine tank through which the fluid to be cooled is adapted to be led, a thermostatic element positioned in said brine tank, said element comprising a pair of dilatation tubes, one of said dilatation tubes having a counter-acting spring associated therewith, the second dilatation tube having a stronger counteracting spring associated therewith, means for feeding a solid cooling material to said brine tank and means connected to said first dilatation tube controlling the rate of feed of said feeding means for said solid cooling material.

5; A heat exchanger comprising a brine tank, a series of tubes extending through said brine tank through which the fluid to be cooled is adapted to be led, a thermostatic element positioned in said brine tank, said element comprising a pair of dilatation tubes, one of said dilatation tubes having a counteracting spring associated therewith, the second dilatation tube having a stronger counteracting spring associated therewith, means for feeding a solid cooling material to said brine tank, a variable speed gear for driving said feeding means and means controlled by said first dilatation tube for varying the speed of said variable speed gear in order to feed said solid material in proportion to the temperature of the brine within said brine tank.

ANDRE LUCIEN DAUPHIN. 

